Third generation (3G) cellular systems are continually being modified to improve the efficiency of transmission of multicast and broadcast services to user equipment (UE). There are various parameters that are desirable to optimize in these cellular systems and networks. Typically, when one of the parameters is optimized, the optimum for another parameter is sacrificed. One of the opposing sets of parameters comprises UE power consumption versus radio resource utilization.
For minimum power consumption, UEs should actively search for signals as infrequently as possible. As shown in FIG. 1, when a UE is not searching for the paging window K or being used by the user for some purpose, it should preferably be in a sleep-mode to minimize power consumption.
Additionally, for efficient radio resource utilization, the same message targeted to multiple UEs should ideally be sent only once. For example, referring to FIG. 2, a plurality of UEs 12, 14, 16 are shown. The UEs 12, 14, 16 are associated with a single group XYZ, which is identified by a single group identifier IDXYZ. The terminology “group identifier” as used hereinafter may refer to a group, a service or any other type of signal that may be associated with one or more recipients or services. The UEs are notified that the group identifier IDXYZ will be transmitted within a certain paging window, for example paging window K shown in FIG. 1. All the UEs targeted for the transmission will then receive that single transmission of IDXYZ in paging window K.
An important consideration is how to satisfy opposing requirements of both the UE power consumption and radio resource utilization to an acceptable degree. It is desirable to optimize both UE power consumption and radio resource utilization so that the sacrifice in each is within an acceptable range.
To satisfy the UE power requirements, the system can transmit multiple message notifications within a synchronized time period. Each broadcast service or message, or target group for a service is assigned an identifier. The UE can search for the identifier to know that a message it should receive is being transmitted. If the UE does not detect the appropriate identifier within a certain time period, the UE can go into a sleep-mode until the next cycle of the time period occurs.
Prior methods of message transmission in cellular systems have had disadvantages which resulted in loss of UE battery life. Although a desirable approach would be to put the group identifiers for all of the different services expected by UE in the same time window, this approach requires that the UE must look for two or more identifiers, which are likely made up of different groups of UEs. While it may be possible to coordinate some of the recipients into the same search window, the majority will often still require multiple windows.
For example, as shown in FIG. 3, a UE may be associated with several groups. As shown in Table 1 below, UE22 is associated with all three groups: ABC, DEF and GHI. Referring to FIG. 4, since IDABC is transmitted in paging window K, IDDEF is transmitted in paging window L and IDGHI is transmitted in paging window M, UE22 will have to be in a waking mode during paging windows K, L and M for each possible message identification. Likewise, UE34 will have to be in a waking mode during paging windows L and M. Accordingly, the number of group services a UE is enabled to receive will therefore dictate the number of awake-periods. This will multiply the battery consumption rate by the number of awake-periods.
TABLE 1GROUPGROUP IDMEMBERSWINDOWABCIDABCUE22, UE24, UE26KDEFIDDEFUE22, UE34, UE36LGHIIDGHIUE22, UE34, UE46M
It would be desirable to provide a method for enabling multicast services and UE battery savings without the shortcomings of the prior art.